The invention relates to devices and techniques for positioning a pointer such as a cursor on a computer display. More specifically, the invention relates to a pointing device such as a track ball that is based upon the Hall Effect.
Numerous pointing devices such as joysticks, mice, track balls, touch pads and the like are well known in the art. Such pointing devices are frequently used to position a cursor or other pointer on an electromagnetic display such as a flat panel display, cathode ray tube (CRT) display, liquid crystal display (LCD), plasma display, or the like. Pointing devices are useful in various computing applications such as games, simulations, control applications, or any other computer application. Track balls are particularly convenient for use as an input device for games, simulations, and control applications because track balls allow precise positioning of pointers, cursors or other objects on a computer display.
Various types of track balls have been used in the prior art. For example, mechanical track balls available from, for example, Pennie and Giles, CTI, and other manufacturers include gear-like mechanisms and switches that allow users to position objects on a display by rotating or otherwise manipulating a mechanical ball. The track ball device senses movement of the ball, and provides a corresponding control signal to the computerized display. Mechanical track balls typically exhibit a noted disadvantage, however, in that the switches and gear-like apparatus can fail or wear over time. Hence the reliability of such devices is suspect, particularly in environments that may be subject to large amounts of dust or other contaminants.
Optical track balls such as those available from the Logitech Corporation of Fremont, Calif. are less susceptible to dust and other contaminants, but such devices include optical guides that may wear or otherwise degrade over time. Moreover, optical track balls may be susceptible to radio frequency (RF) interference or other forms of interference. Hence even optical track balls are not suitable for all situations.
It is therefore desired to create a pointing device using a new sensor technology that is not susceptible to the disadvantages of prior art pointing devices.
In various embodiments of the invention, an improved track ball suitably includes one or more field-producing elements that produce or respond to electro-magnetic fields in accordance with the Hall Effect. Hall Effect sensors in proximity to the track ball sense changes in the electro-magnetic field or in the Hall Effect, and produce corresponding output signals. The output signals may be used, for example, as a control input to a digital computer for such applications as games, simulations, or control applications such as controls for an aircraft or other vehicle.